The subject matter disclosed herein relates to an aircraft and, more particularly, to an aircraft with a power limiting generator control unit (GCU).
Typically, an aircraft's electrical power system includes a DC power generator as a primary power source with batteries serving as an emergency backup power source. The DC power generator is used to start an aircraft's engine and, once started, the engine provides for power generation through the power generators resulting in electrical power being supplied to load busses in the electrical power system. A typical twin engine generator power system would consist of two generators, one per engine. A first generator would be used for starting the first engine and for providing, for example, electrical power to left hand busses. A second generator would be used for starting the second engine and providing power to right hand busses. In the event that the first generator was to fail, the power system would compensate by providing power to all buses through the remaining generator. In some cases, the remaining load busses can overload the remaining generator, resulting in its failure as well. Most power systems, therefore, also include a battery backup for providing supplemental power to if one or both of the generators fail. The battery feeds power to the emergency busses and the essential busses.
In some cases, such as failure of a single engine in a twin engine aircraft, it may be necessary to use the generator for the working engine as a starter for the non-working engine in a cross-starting scenario. This can apply extreme loads on the working engine and reduces its surge margin and acceleration capabilities. That is, modern engines have limited generator available loads and any power taken off the generator typically costs 3 to 5 times as much power as if it was taken off of the power turbine.